mmg_233_2013_genetics_genomicswikiaorg-20200214-history
Genomic analysis of Pseudomonas aeruginosa virulence
Pseudomonas aeruginosa is a ubiquitous Gram-negative rod-shaped bacterium. It is an opportunistic pathogen, causing infections ranging from cosmetic skin infections to life threatening pneumonia in immunodificient or immunocompromised population 4. PAO1 and PA14 are two important laboratory adapted P. aeruginosa strains. Both of these strains are originally clinical isolates, while PA14 has a stronger virulence than PAO1 3. The genes of virulence in bacteria are usually located on specific pathogenicity islands; an example of such pathogenicity islands is SCC''mec'', which gives methicillin-resistancy to strains of Staphylococcus aureus5. In the following is a genomic analysis of PAO1 and PA14 to identify the potential PA14 specific gene clusters that give this strain higher virulence. Similarity and difference between the genome of PAO1 and PA14 The sizes of PAO1 and PA14 genomes are very similar: approximately 91.7% of PA14 genome exists in PAO1, and 95.8% PAO1 genome exists in PA14 1. PA14 has a slightly larger genome than PAO1 (6.5 Mb versus 6.3 Mb) 1. There is one major rearrangement between the genomes of the two strains. The sequence between two ribosomal RNA clusters is inversed in PAO1 compared to that in PA14. The large inversion also exists in other strains shown in the research, all of them resemble PA14 instead of PAO1, indicating the PA14 genome is more typical in Pesudomonas species 1. Testing the virulence of P. aeruginosa strains by Caenoehabditis elegans ''model The nematode ''Caenohabiditis elegans ''was utilized as a model host to test the different virulence of 20 ''P. aeruginosa strains, including PA14 and PAO1. Among these strains, PA14 is the second most virulent strain and PAO1 is ranking 11, indicating it is a moderately virulent strain 1. A microarray based genomic analysis was performed to identify the prevalence of PA14 specific genes and PAO1 specific genes. However, the results indicated that there is no strong relation between the PA14 specific genes and virulence. And the virulence does not correlate with genome similarity between strains 1. Subsequently, a transposon mutagenesis is performed to PA14 strain to identify the genes associated with virulence. Mutants with decreased virulence are screened and nine genes were identified. However, these genes are not PA14 specific, nor are they specific for other high-virulence strains 1. Conclusion The results showed that the high virulence strain PA14 has a remarkably similar genome with the moderate virulent strain PAO1, although there is a major reversion within the genome 1. There are no such strain specific genes associated with the virulence of PA14, and the virulence relation does not correlates to genome similarity between different strains. The virulence of'' P. aeruginosa is both multifactorial and combinatorial 1. References 1. Lee, D. G. ''et al. Genomic analysis reveals that'' Pseudomonas aeruginosa'' virulence is combinatorial. Genome Biol. 7, R90 (2006). 2. Stover, C. K. et al. [http://www.nature.com/nature/journal/v406/n6799/full/406959a0.html Complete genome sequence of Pseudomonas aeruginosa PAO1, an opportunistic pathogen. ] Nature 406, 959–64 (2000). 3. Labauve, A. E. & Wargo, M. J. Growth and Laboratory Maintenance of Pseudomonas aeruginosa. 1–8 (2012). doi:10.1002/9780471729259.mc06e01s25 4.http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa 5. http://en.wikipedia.org/wiki/SCCmec